The invention relates to a fuel injection pump for internal combustion engines as described hereinafter. Injection pumps having pump cylinders disposed in series, also known as series injection pumps, have been manufactured on a very large scale all over the world for decades and have heretofore quite satisfactorily attained the required accuracy in fuel quantity metering. However, with the greatly elevated injection pressures needed to apply modern injection methods to Diesel engines, and the ever-more stringent exhaust emission regulations and the resultant increasingly stringent requirements for accuracy in fuel metering on the part of the individual pump elements, it has proved to be disadvantageous that the pump elements connected to a common suction chamber furnish varying injection quantities, especially during full-load engine operation, unless at least a partial correction is made by means of an expensive, iterative adjustment process which preferably should be avoided. These deviations in fuel quantity arise because between the inlet and the outlet of the fuel inside the pump housing, partial heating of the fuel takes place, due particularly to the quantities of fuel that are diverted at high pressure at the end of fuel supply. Because of the different temperatures and the altered density and compressibility of the fuel, this causes corresponding deviations in fuel supply quantities per stroke of the pump piston, and hence causes the output of the various engine cylinders to differ from one another.
In a fuel injectin pump of the same generic type, known from German Offenlegungsschrift No. 25 47 071, the common suction chamber that had been known until then was subdivided into a plurality of partial suction chambers, one being associated with each pump cylinder, and each being supplied separately with fuel via an inlet conduit that was separate from the return-flow conduit. Since the respective inlet element to the partial suction chambers is molded in the housing by casting and is very large in size, and since the throughput through the partial suction chambers is metered by respective throttled return-flow cross sections, it is unavoidable in this design that the discharge fuel, which emerges at high pressure and is heated up to a corresponding extent, will mix with the fresh, incoming fuel, thus causing uncontrollable heating and mixing in the inlet conduit despite the provision of separate partial suction chambers.